Rotary switch



P 1950 K. w. GRAYBILL ETAL 2,522,715

ROTARY swrrcn Original Filed larch 15, 1946 2 Sheets-Sheet 1 INSULATION l3 I5 14 FIG.I

FIG.2

1 INVENTORS KENNETH W. GRAYBILL y HANS iNGEBlBCH ATTORNEY p 1950 n w. GRAYBILL ETAL 2,522,715

ROTARY SWITCH Original Filed larch 15, 1946 2 Sheets-Sheet 2 FI G.6

FIG.7A

FIG.7

INVENTORS. KENNETH W. GRAYBILL HANS' SENGEBUSOH ATTORNEY Patented Sept.

ROTARY SWITCH Kenneth W. Graybill, Elmhurst, and Hans Sengebusch, Villa Park, Ill., assignors to Automatic Electric Laboratories, Inc., Chicago, 11]., a corporation of Delaware Original application March 15, 1946, Serial No. 654.556. Divided and this application January 17, 1948, Serial No. 2,904

4 Claims.

The present invention relates in general to electrical switches and more particularly to rtary switches of the step-by-step type, and is a division of our prior application Serial No. 654,556, filed March 15, 1946.

It is an object of the invention to provide a rotary switch which will operate very reliably at higher speeds than heretofore possible.

Another object is to provide an improved rotary switch which will be simple and economical to construct, but which will be very rugged so that it has a long operating life. A further object is to simplify the assembling of such a switch by reducing the amount of manual adjustment needed to bring the parts thereof into their correct relationship.

In keeping with this last object, it is one feature of the invention to mount all the component parts of the switch upon a one-piece frame, this frame being so formed as to automatically position the bank contacts, wipers, electromagnet and the associated armature in their correct relationship.

Another feature is the provision of a novel arrangement for supporting one end of the wiper shaft. whereby that end may be freed from its support easily and without the use of tools.

Another feature is the rovision, in a reverse drive rotary switch, of a novel relationship between the driving spring and the electromagnet for tensioning same, whereby upon deenergization of the eleetromagnet the spring is capable of delivering a greater amount of energy to advance the switch wipers.

A further feature resides in the provision of an improved arrangement for positively halting the switch wipers in the correct position at the end of each step.

Other objects and features will be pointed out in the course of the following detailed description of the invention, taken in connection with the accompanying drawings, in which:

Fig. 1 is a front elevation of the switch according to the invention, certain wipers and bank contacts having been omitted for the sake of clarity,

Figs. 2 and 3 are side elevations showing opposite sides of the switch,

Fig. 4 is a fragmentary view of the bottom of the switch,

Fig. 5 is an enlarged view of the wiper assemly.

Fig. 6 is a cross-sectional view taken along the line 6-6 of Fig. 5,

Fig. 6A is a fragmentary cross-sectional view z of the wiper assembly showing a'modifled construction, and V Figs. 7, 7A and 7B are greatly enlarged views of a part of the switch mechanism showing-successive positions occupied thereby during movement of the switch.

Referring now more in detail to the drawings, all parts of the switch are mounted upon a onepiece frame It which is stamped'from sheet steel or other suitable material and formed as "shown. A pair of oppositely disposed flanges H drilled and tapped as at l2 are provided on'the frame to facilitate mounting same on any desiredsupport (not shown). I

To the left of these flangesiFig. 2) the frame is arcuate in shape and carries a bank of sta tionary contacts I3 which are arranged in levels or rows. There are twenty-five contacts in each level, and adjacent levels are separated from one another by insulators It and spacers I 5. Ten levels are shown, but it will be understood that any desired number may be arrangedas illustrated, these being secured to the frameby elongated screws it which pass through suitable holes in the frame and corresponding holes in the insulators I4 and spacers l5. As indicated by dotted lines in Fig. 3, the individual contacts are so shaped as to avoid being short-circuited by these screws. Each contact in the bank is provided at its outer end with a flared soldering lug and is disposed along a line radial to the axis of the wiper assembly now to be described. I This assembly includes a stationary spindle or shaft ll one end of which is rigidly secured to the switch frame by means of a flanged stud I8 and a nut l9. As shown in Fig. 6, the stud is threaded on the inside to receive shaft l1 and is threaded on the outside to receive nut iii, the latter being tightened down after the stud has been inserted in a slot 2| in the switch frame and centered with respect to ban: contacts l3. Mounted on the stationary spindle I1 is a rotatable hollow shaft or sleeve member 22 having integral therewith or rigidly aillxed thereto) a toothed ratchet wheel 23. A square nut 20 screwed onthe end of spindle i1 prevents axial movement of the rotary member. Carried by sleeve 22 but insulated therefrom by a tubular insulator 24 are a. series of disc-like wiper-carrying hubs 28, a spacer 26 and a drum 21; these are separated from one another by insulating washers 28 and are tightened down against the toothed wheel by means of a nut 29 so that they are rigid with respect to the rotary member.

A shallow internal recess ii is provided in one face of each wiper-carrying hub so that the distance along the surface of the tubular insulator 24 from one hub to the adjacent hub is increased, with a corresponding increase in leakage resistance between the two. Each hub also has two oppositely disposed peripheral recesses 32 in which are seated a pair of double-en .ed wiper blades 33 shaped as illust 'ated in Fig. 5. These blades are rigidly secured to their associated hubs as by spot welding, and it will be noted that the recesses 32 in which they are seated are slightly deeper than the thickness of the blades themselves so that variations in the thickness of the blades due to ordinary manufacturing tolerances will not affect the spacing of the adjacent ones of the hubs. The importance of this mode of construction will be self -evident since the wipers must be spaced along the shaft with reat exactness to coincide with the spacing of the different levels of bank contacts. In practice excellent results have been obtained by machiningthe hubs approximately to the desired thickness, welding the wiper blades thereto and then squeezing or compressing the hubs to exact thickness in a power press.

Returning again to the square nut 20 which prevents axial movement of the rotatable portion of the wiper assembly, this is locked in position on the stationary shaft H by means of a flat spring member 34 mounted on the contact bank as shown in Figs. 3 and 6'. A suitable square opening near the free end of the spring member normally fits over the nut 20 preventing rotation thereof; this also serves to assist in keeping the spindle l'l properly centered with respect to the contacts I3. A bent-overlug 35 at the extreme end of the spring member is provided with an index line 38 which is adapted to register with numbered markings on the drum 2! in order to facilitate determining the rotary position occupied by the wipers at any time. Application of finger pressure to a second lug 31 on the spring member will deflect same as shown by dotted lines in 'Fig. 6, permitting the entire wiper assembly to be drawn away from the frame and the associated contact bank if nut I9 is loosened slightly.

An alternative mode of construction is shown in Fig. 6A. According to this, no nut is provided on the end of spindle H to prevent axial movement of the hollow shaft 22. Instead, spring 34' is provided with a bushing 20' which it is tcnsioned to press against the end of the hollow shaft to prevent endwise displacement thereof. As indicated, there is a circular recess in the bushing which is adapted to receive the end of spindle I! and maintain same centered with respect to the bank contacts. The spring 34' may be deflected in the same way as that in Fig. 6, to free the end of the wiper assembly.

The wipers are moved in steps under control of an elcctromagnet 4| which is rigidly secured to the switch frame by means of a screw 42. As best seen in Fig. 3, a portion of the frame is bent over to form an L-shaped heel piece for this magnet. Associated with the magnet is pivotal magnetic armature 43 which is supported on the frame by means of a non-magnetic yok 44 and a bearing pin 45. said yoke being rigidly secured to the heel piece by means of two screws as shown. The armature is provided with an elongated lever arm 46 having at its extreme end a toothed portion 41 adapted to mesh with the teeth on wheel 23.

A heavy compression spring the two ends of which are coiled about a pair of flanged centermg studs 52 and 53. urges the lever arm toward wheel 23. The stud 52 is provided with a threaded shank which screws into a tapped hole in an arm 54 on the switch frame; this permits the stud to be advanced or retracted to change the spring tension on m 46, it being understood that unintended changes in such spring tension are prevented by means of a lock-nut 55 which is tightened down after the tension has been properly adjusted.

Pivotally mounted on the lever arm 45 at a point 56 is a pawl 51 which is urged toward the toothed wheel 23 by alight coiled spring 58. When the electromagnet 4| is energized, it attracts armature 43 against the tension of spring 5|, causing the pawl tip to move over one tooth of wheel 23 and lodge in the next notch, while at the same time the toothed portion 41 of the lever arm moves away from wheel 23. A flat spring 59 secured to the contact bank prevents retrograde movement of the wiper assembly during this operation. Upon the subsequent de-energization of the electromagnet, spring 5! quickly restores lever arm 46 to normal causing pawl 51 to advance the toothed wheel and the associated wipers toward their next contact position. As the rotary member reaches said next position, the toothed portion of the lever arm once more meshes with the teeth of wheel 23 so that the wipers (which now are moving very rapidly) will not be carried beyond that position due to acquired momentum.

The manner in which the toothed portion of the lever arm re-engages the toothed wheel is illustrated quite clearly in Figs. '7, 7A and TB. which show these elements in three successive positions near the end of the lever arms return stroke. A particular tooth on each element is identified by a dot in all three figures, making it easy to understand the relative movement of the two elements. In Fig. 7, the toothed portion 41 is just outside the path of the teeth on wheel 23 and both are moving in the direction indicated by their respective arrows. Fig. 7A shows how the two sets of teeth clear one another as they begin to mesh, while Fig. 7B illustrates their final position, wherein rotation of wheel 23 is halted by the toothed portion of the lever arm.

It will be realized that the pull of the electromagnet 4! upon its armature 43 is not constant throughout the movement of the armature toward the core of the electromagnet. Instead as the armature approaches the core, the attractive force between the two increases at an accelerated rate, the change in this force bearing a nonlinear or exponential relationship to the space displacement of the armature from its starting position. To take the fullest advantage of the increased pull which thus occurs as the armature nears the end of its stroke, spring 5| is specially designed to have a non-linear force/displacement characteristic approximating the force/displacement characteristic of the electromagnet and its associated armature, whereby a greater amount of energy is stored in the spring for a given final displacement of the armature than otherwise would be the case. As a result, an increased amount of energy is available to drive the wipers upon deenergization of the electromagnet, and in practice this has been found to contribute very materially to the speed at which the wipers are stepped.

A pair of divergent brushes 60 is provided for each pair of wiper blades. These are mounted on the contact bank as shown in Figs. 1 and 3 and make electrical contact with their associated wipers in all positions thereof, engaging same as shown in Fig. 5. The armature 43 is provided with a second lever arm Bl which operates a set of auxiliary contacts 82. In the drawings, this contact set is illustrated as a single pair of contacts which are separated upon the energization of the electromagnet, but it will be appreciated that any desired other set of contacts might be employed. A second auxiliary set of contacts 63 are mounted on the contact bank by means of a detachable mounting plate 84; these are operated by a pair of pins 85 rigidly affixed to the drum 21 at two diametrically opposite points thereon. Preferably, pins 65 are so located as to operate the associated contact set when the wipers occupy their home position, as shown in Fig. 3.

Having described the invention, what we believe to be new and desire to protect by Letters Patent is set forth in the following claims.

What is claimed is:

1. In a rotary switch, a hollow wiper-carrying shaft rotatably supported upon an elongated spindle, means supporting one end of said spindle, and a flat spring having an opening which fits over the other end of said spindle so that said spring presses against said hollow shaft to prevent axial movement thereof, said spring being the sole support of said other end of said spindle and being yieldable axially thereof to free said other end thereof.

2. In a rotary switch, a hollow wiper-carrying shaft rotatably supported upon an elongated spindle, means supporting one end of said spindle, means including a member screwed on the other end of said spindle for preventing axial movement of said hollow shaft on said spindle, and an element being the sole support of said other end of said spindle and locking said member in 6 place thereon, said element yieldable axially of said spindle to unlock said member.

3. In a rotary switch, a rotatable wiper-carrying shaft, means at each end of said shaft for supporting same, the sole supporting means at one end of said shaft comprising a flat spring member normally disposed in a plane perpendicular to the axis of said shaft and yieldable axially of said shaft to free said one end thereof, an index mark on said spring member, adrum connected to said shaft and rotated thereby, said drum having different markings adapted to register with said index mark in different angular positions of said shaft.

4. A rotary switch as claimed in claim 3 including a pair of projecting members rigidly affixed to said drum at two diametrically opposite points thereon, and auxiliary contacts associated with said switch and actuated by one of said pair of said projecting members when said shaft has assumed a certain first angular position, said contacts actuated by the other projecting member of said pair when said shaft has assumed a 4 certain second angular position.

KENNETH W. GRAY'BILL. HANS SENGEBUSCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,194,051 Muller Mar. 19, 1940 FOREIGN PATENTS Number Country Date 244,458 Great Britain Mar. 7, 1927 358,293 Great Britain Oct. 8, 1931 

